CCL-4 enhances prostate cancer migration and invasion by modulating integrin expression

Prostate cancer (PCa) is the second leading cause of cancer-related deaths in men in the United States and is the most commonly diagnosed non-cutaneous cancer. CCL4 is a secreted chemokine that is over expressed in patients that show PCa recurrence after prostatectomy. Currently, no reported evidence shows the biological role of CCL4 in PCa progression. We studied the role of CCL4 in PCa progression using in vitro and in vivo models. PC3 and 22RV1 PCa cell lines were treated with CCL4 at 0.001 ng/mL and 0.1 ng/mL and subjected to migration and invasion assays. Tumor progression was evaluated using a xenograft model in which the anterior prostate lobes of SCID mice were injected with 250,000 22RV1 cells. CCL4 was administered bi-weekly with intraperitoneal injections. Tumor tissue was collected for immunohistochemical and gene expression analysis. In vitro studies showed that CCL4 increased invasion and migration of PCa cells. In vivo studies demonstrated that CCL4 increased tumor volume. Immunohistochemical analysis showed that these tumors expressed higher levels of desmin and phosphohistone 3 (pH3), and showed increased angiogenesis. Gene expression analysis showed that CCL4 increased the expression of genes associated with metastasis. Western blot analysis showed that CCL4 increased integrin expression and FAK phosphorylation suggesting integrin pathway activation. This suggests that CCL4 is important for negative outcomes such as metastasis and PCa recurrence.